In her new book, “What Happened,” Clinton blames Sanders for doing “lasting damage” to her campaign, but the Vermont senator hit back at his primary opponent in an appearance on “The Late Show with Stephen Colbert” Thursday.

“Our job is to go forward,” he said.

A leaked excerpt from Clinton’s book, due out Sept. 12, described Sanders as a disruptive, counterproductive force and has grabbed headlines this week.

But Sanders said he isn’t really concerned with Clinton’s version of what happened or why she lost the 2016 presidential election.

“Look, Secretary Clinton ran against the most unpopular candidate in the history of this country and she lost and she was upset about it and I understand that,” the senator said. “But our job is really not to go backward. It is to go forwards.”

Nine months into President Donald Trump’s reign, Sanders seemed fed up with the continual post-mortem on the election that won Trump the Oval Office, noting the country is facing “enormous problems.”

“I think it’s a bit silly to keep talking about 2016,” Sanders said.

Those problems include healthcare, educational opportunities and wages, to name a few, Sanders said.

Though the Vermont senator has been spotted in Iowa in July and in New Hampshire this month, but wouldn’t say whether he was making another bid for the presidency.

“Right now what the American people want the Senate and House to do is to is start addressing the real issues that they are facing and the real issues are healthcare, making educational opportunity available to all, raising minimum wage — that is what they want us to focus on. They do not like never-ending campaigns,” he said.

His chances might be pretty good if he runs again, though. A recent Harvard-Harris poll showed Sanders is the only U.S. politician whom a majority of American voters view favorably. The poll gave Sanders a favorability rating of 54 percent.

Watch the second half of Stephen Colbert's interview with Bernie Sanders below: